fnchooft / yaws_rest

Simple rest-endpoint (airport) with embedded-yaws using rebar3

yaws_rest

Implementation of Chapter 4.1 from:

Building Web Applications with Erlang
by
Released June 2012
Publisher(s): O'Reilly Media, Inc.
ISBN: 9781449309961

Alterations

The older rest-module example was using rfc4627.erl which could not be found. The latest version from YAWS comes with its own json2-parser.

20210407: The lastest master branch from git://github.com/erlyaws/yaws.git now contains the json2-obj_fetch/3 function.

The differences from the original O-Reilly rest file vs the newer rest_airport.erl:

$ diff rest.reference rest_airport.erl -y --suppress-common-lines
-module(rest).						      |	-module(rest_airport).
-include("/usr/lib/erlang/lib/stdlib-1.17.3/include/qlc.hrl") |	-include_lib("stdlib/include/qlc.hrl").
-include("/usr/lib/yaws/include/yaws_api.hrl").		      |	-include_lib("yaws/include/yaws_api.hrl").
-export([out/1, addAirport/4, handle/2]).		      <
%-compile(export_all).					      <
							      >	-include("../include/rest_airport.hrl").
-define(RECORD_TYPE,      airport).			      <
-define(RECORD_KEY_FIELD, code).			      <
-record(?RECORD_TYPE,					      |	-export([out/1, addAirport/4, handle/2,do/1]).
        {?RECORD_KEY_FIELD, city, country, name }).	      |	%-compile(export_all).
    Data = [{obj, 					      |	    Data = [{struct, 
    JsonData = {obj, [{data, Data}]},			      |	    JsonData = {struct, [{data, Data}]},
    rfc4627:encode(JsonData).				      |	    json2:encode(JsonData).
    {ok, Json, _} = rfc4627:decode(Arg#arg.clidata),	      |	    io:format("~n ~p:~p POST Arg:~p ~n", [?MODULE, ?LINE,Arg]
							      >	    
							      >	    {ok, Json} = json2:decode_string(binary_to_list(Arg#arg.c
    Airport	= rfc4627:get_field(Json, "airport", <<>>),   |	    Airport	= json2:obj_fetch("airport",Json, <<>>),
    City	= rfc4627:get_field(Json, "city", <<>>),      |	    City	= json2:obj_fetch("city",Json, <<>>),
    Country	= rfc4627:get_field(Json, "country", <<>>),   |	    Country	= json2:obj_fetch("country",Json, <<>>),
    Name	= rfc4627:get_field(Json, "name", <<>>),      |	    Name	= json2:obj_fetch("name",Json, <<>>),
    {ok, Json, _} = rfc4627:decode(Arg#arg.clidata),	      |	    {ok, Json} = json2:decode_string(binary_to_list(Arg#arg.c
    Airport	= rfc4627:get_field(Json, "airport", <<>>),   |	    Airport	= json2:obj_fetch("airport",Json, <<>>),
    City	= rfc4627:get_field(Json, "city", <<>>),      |	    City	= json2:obj_fetch("city",Json, <<>>),
    Country	= rfc4627:get_field(Json, "country", <<>>),   |	    Country	= json2:obj_fetch("country",Json, <<>>),
    Name	= rfc4627:get_field(Json, "name", <<>>),      |	    Name	= json2:obj_fetch("name",Json, <<>>),

1. Notice the include_dir imports due to using rebar3
2. Notice the new rest_airport.hrl to extract record-definition
3. Notice use of different api rfc4627 vs json2 NOTE: The alteration in yaws/json2.erl is needed for this code

Build

$ rebar3 get-deps
$ rebar3 compile

Running

$ rebar3 shell

Then inside the shell execute:

> observer:start().

This will allow you to inspect the supervision-tree.

Testing

1. GET:

$ curl -X 'GET' 'http://localhost:8888/rest/airport' -H 'Content-Type: application/json'
{"data":""}

2. POST

curl -X 'POST' 'http://localhost:8888/rest/airport' -H 'Content-Type: application/json' -d '{ "airport": "JFK", "city": "New York", "country": "US", "name": "John F Kennedy" }'
{ "airport": "JFK", "city": "New York", "country": "US", "name": "John F Kennedy" }

3. GET

curl -X 'GET' 'http://localhost:8888/rest/airport' -H 'Content-Type: application/json'
{"data": [{ "airport": "JFK", "city": "New York", "country": "US", "name": "John F Kennedy" }]

Links

• http://yaws.hyber.org/embed.yaws
• https://www.oreilly.com/library/view/building-web-applications/9781449320621/ch04.html#rest